A fire protection system may comprise a sprinkler system and/or a standpipe system. A sprinkler system is an active fire protection measure that provides adequate pressure and flow to a water distribution piping system, onto which a plurality of fire sprinklers is connected. Each closed-head sprinkler can be triggered once an ambient temperature around the sprinkler reaches a design activation temperature of the individual sprinkler head. In a standard wet-pipe sprinkler system, each sprinkler activates independently when the predetermined heat level is reached. Because of this, the number of sprinklers that operate is limited to only those near the fire, thereby maximizing the available water pressure over the point of fire origin.
A standpipe system is another type of fire protection measure consisting of a network of vertical piping installed in strategic locations within a multi-story building. The vertical piping may deliver large volumes of water to any floor of the building to supply hose lines of firefighters, for example.
FIG. 1 illustrates a block diagram of a prior art fire protection installation 50. A fire pump 52 boosts water pressure of a water source 54 by transferring energy to the water. The increase in water pressure acts to move the water into a fire protection system 56. A fire pump controller 58 serves to automatically govern, in some predetermined manner, the starting and stopping of the fire pump 52 and to monitor and signal the status and condition of the fire pump 52 (consisting of a pump and a driver), the fire pump controller 58, and accessories. A pressure maintenance pump or jockey pump 60 serves to maintain the pressure on the fire protection system 56 between preset limits when the fire pump 52 is not flowing water. A pressure maintenance pump controller (or jockey pump controller) 62 serves to automatically govern, in some pre-determined manner, the starting and stopping of the jockey pump 60 and to monitor and signal the status and condition of the jockey pump 60 (consisting of a pump and a driver) and the jockey pump controller 62. Check valves, such as check valve 64, are used in the fire pump installation 50 to allow the flow of water in one direction only for the purpose of building pressure in the fire protection system 56. Check valves are installed between the outlets of each of the pumps and the fire protection system 56. Gate valves, such as gate value 66, are installed on the inlets and outlets of each of the pumps and are used to isolate either of the two pumps from the fire protection system 56 for maintenance purposes.
The output of the jockey pump 60 is connected to the system side of the check valve in a typical fire pump installation. The main function of the jockey pump 60 is to maintain system water pressure by automatically cycling between pressure set points. That is, the jockey pump 60 will maintain water pressure in the fire protection system 56 by automatically cycling on and off between predetermined, independent START and STOP pressure settings. In this way, the jockey pump 60 functions to make up for small leaks in the system and thereby helps to prevent the larger fire pump from nuisance cycling. Ordinarily, then, the START and STOP settings of the jockey pump 60 are set well above those of the fire pump 52 so that the jockey is cycling to maintain pressure against normal leaks.
The fire pump installation 50 includes the fire pump 52 connected to the water source 54 by way of the gate valve 66. The water source 54 provides water flow at a pressure to sprinkler system risers and hose standpipes. Generally, fire pumps are needed when the water supply cannot provide sufficient pressure to meet hydraulic design requirements of the fire sprinkler system. This usually occurs in a building that is tall, such as in high-rise buildings, or in systems that require a relatively high terminal pressure at the fire sprinkler to provide a large volume of water, such as in storage warehouses.
The fire pump 52 starts when a pressure in the fire protection system 56 drops below a certain predetermined start pressure (low pressure). The pressure in the fire protection system 56 may drop significantly when one or more fire sprinklers are exposed to heat above their design temperature, and opens, releasing water. Alternately, fire hose connections to standpipe systems may be opened by firefighters causing a pressure drop in the fire protection system 56. The fire pump 52 may have a rating between 3 and 3500 horsepower (HP).
The jockey pump 60 is intended to maintain pressure in the fire protection system 56 so that the larger fire pump 52 does not need to constantly run. For example, the jockey pump 60 maintains pressure to an artificial level so that the operation of a single fire sprinkler will cause a pressure drop that will be sensed by the fire pump controller 58, causing the fire pump 52 to start. The jockey pump 60 may have a rating between ¼ and 100 horsepower (HP).
The jockey pump 60 may maintain pressure above the pressure settings of the larger fire pump 52, so as to prevent the main fire pump 52 from starting intermittently. For example, the jockey pump 60 provides makeup water pressure for normal leakage within the system (such as packing on valves, seepage at joints, leaks at fire hydrants, or leakage within the system such as backward flow through check valves 64, from the system 58 toward the lower pressure source 54), and inadvertent use of water from the water supply. When the fire pump 52 starts, a signal may be sent to an alarm system of the building to trigger the fire alarm. Nuisance operation of the fire pump 52 eventually causes fire department intervention. Nuisance operation of the fire pump 52 also increases wear on the main fire pump 52. Thus, it is generally desired to either reduce and/or avoid any nuisance or unintended operation of the fire pump 52.
In the United States, the application of the jockey pump 60 in a fire protection system is provided by NFPA 20: Standard for the Installation of Stationary Pumps for Fire Protection, which prohibits a main fire pump or secondary fire pump from being used as a pressure maintenance pump.
Each of the fire pump 52 and the jockey pump 60 include pump controllers, which may comprise a microprocessor-based controller that can be used to adjust start and stop set points.
As just one example, as early as January 2001, microprocessor-based jockey pump controllers were provided by Firetrol, Inc. of Cary, N.C. These microprocessor-based pump controllers or jockey pump controllers were typically housed in an industrial enclosure, included a digital display and received pressure information by way of a solid state pressure sensor, typically via 1-5 Vdc. Using the electronic pressure monitors, water pressure can be measured with a pressure transducer providing an output of 1-5 Vdc for ranges of 0-300 and 0-600 psi. Operation of the pumps could be controlled via programmable set points. Such set points for each pump include start and stop pressures, and on-delay, minimum run, and off-delay timers. An additional output is provided for a call to start indicating a low pressure condition, and a remote stop/reset input is provided for reset of all timing functions.
The jockey pump controller 62 may have a start pressure set point of approximately five to ten pounds per square inch greater than the start pressure set point in the fire pump controller 58. In this manner, the jockey pump controller 62 cycles the jockey pump 60 to maintain the system at a predetermined pressure well above the start setting of fire pump 52 so that the fire pump only runs when a fire occurs or the jockey pump 60 is overcome by a larger than normal loss in system pressure.